BIO 322 Exam 2 ASU UPDATED ACTUAL Questions and
CORRECT Answers
Population trend: How do we know if population size is A. Estimate trend in N from historical records; or reconstruct past N from
stable, increasing, or declining through time? (look at modern-day allelic diversity (or use both methods)
lecture slides for each because it is too long, equations lambda > 1 population grows
are easier to look over on them) lambda = 1 population stable
lambda < 1 population shrinks
B. Estimate population trends using time-series data
C. Estimate population trends using a statistical method such as simple linear
regression
D. Estimate population trends using a demographic matrix model
biology of rarity Conservation Science is concerned with the distinctive problems faced by small
populations because population size (N) is inversely related to risk in terms of
amount of genetic variation and numbers of individuals. We will call this the
biology of rarity.
Perils of small populations 1) demographic stochasticity
2)Environmental stochasticity
3) Allee Effect
4) Inbreeding
5) Genetic drift
all lead to greater risk of extinction
What is demographic stochasticity? variation in birth rates and death rates due to random differences among
individuals
What is the Allee effect? - A form of positive density-dependent feedback in which as N declines, per
capita population growth rate declines
- Happens due to:
1) Mate finding or pollination problems
2) Cooperative hunting suffers
3) Protection from predators declines
4) Disrupts social interactions (courtship displays, communal rearing of young)
Inbreeding breed from closely related people or animals, especially over many generations
and therefore loss of diversity over time
What is genetic drift? The frequency of alleles with the same fitness may change at random through
time in a process called genetic drift. If there are two alleles at a locus, and they
have the same fitness, random sampling can cause their relative frequencies in a
population to change. Genetic drift has important consequences for the random
substitution of genes and the Hardy-Weinberg equilibrium.
What is environmental stochasticity? Unpredictable changes in the environment that can cause extinction of small
populations
, What is the most critical attribute defining degree of Population size
endangerment for the ICUN?
What is the extinction vortex? - a small population declines and becomes more vulnerable to processes that
lead to extinction like habitat destruction, pollution, over-harvesting, or invasive
species
- often multiple, simultaneous, or repeated impacts to most or all populations that
cause extinction
effective population size An estimate of the size of a population based on the numbers of females and
males that successfully breed; generally smaller than the total population.
relationship between effective pop. size and time the smaller the population, the more heterozygosity lost over time
(genetic heterozygosity in a population)
Why is demographic stochasticity an important cause of every individual contributes a lot to the population's chance of survival when
extinction for small populations ONLY? populations are small
What five assumptions are required for creating an ideal 1) Discrete generations
population? 2) Completely random mating
3) Nm = Nf (even sex ratio)
4) Random family sizes
5) Constant population size
If a population is not ideal, convert N to Ne and then calculate the rate of loss of
H. It is almost always the case that Ne < N
Which of the following risks is the result of random demographic stochasticity: random variation among individuals in birth rate, death
variation in the survival and production of offspring and is rate, and sex of offspring. (declines quickly with population size)
especially of concern for a small population?
Why do conservation scientists care about genetic 1) Long-term: evolutionary potential
diversity within species? -populations may diverge into new subspecies or even full species
2) Long-term: evolutionary flexibility
-ability to respond to epidemics, climate change
3) Short-term: individual and population health
-genetic diversity improves an individual's fitness
Two measures of genetic diversity 1) Polymorphism: number of loci for which >1 allele exists
2) Heterozygosity: average percentage of loci that are heterozygous or
heterozygous at a particular locus
What three factors affect heterozygosity? Sex ratio, mating structure, population variability through time
Why do small populations lose genetic diversity over Little new genetic diversity emerges because mutations are rare and gene flow is
time? limited/non-existent
CORRECT Answers
Population trend: How do we know if population size is A. Estimate trend in N from historical records; or reconstruct past N from
stable, increasing, or declining through time? (look at modern-day allelic diversity (or use both methods)
lecture slides for each because it is too long, equations lambda > 1 population grows
are easier to look over on them) lambda = 1 population stable
lambda < 1 population shrinks
B. Estimate population trends using time-series data
C. Estimate population trends using a statistical method such as simple linear
regression
D. Estimate population trends using a demographic matrix model
biology of rarity Conservation Science is concerned with the distinctive problems faced by small
populations because population size (N) is inversely related to risk in terms of
amount of genetic variation and numbers of individuals. We will call this the
biology of rarity.
Perils of small populations 1) demographic stochasticity
2)Environmental stochasticity
3) Allee Effect
4) Inbreeding
5) Genetic drift
all lead to greater risk of extinction
What is demographic stochasticity? variation in birth rates and death rates due to random differences among
individuals
What is the Allee effect? - A form of positive density-dependent feedback in which as N declines, per
capita population growth rate declines
- Happens due to:
1) Mate finding or pollination problems
2) Cooperative hunting suffers
3) Protection from predators declines
4) Disrupts social interactions (courtship displays, communal rearing of young)
Inbreeding breed from closely related people or animals, especially over many generations
and therefore loss of diversity over time
What is genetic drift? The frequency of alleles with the same fitness may change at random through
time in a process called genetic drift. If there are two alleles at a locus, and they
have the same fitness, random sampling can cause their relative frequencies in a
population to change. Genetic drift has important consequences for the random
substitution of genes and the Hardy-Weinberg equilibrium.
What is environmental stochasticity? Unpredictable changes in the environment that can cause extinction of small
populations
, What is the most critical attribute defining degree of Population size
endangerment for the ICUN?
What is the extinction vortex? - a small population declines and becomes more vulnerable to processes that
lead to extinction like habitat destruction, pollution, over-harvesting, or invasive
species
- often multiple, simultaneous, or repeated impacts to most or all populations that
cause extinction
effective population size An estimate of the size of a population based on the numbers of females and
males that successfully breed; generally smaller than the total population.
relationship between effective pop. size and time the smaller the population, the more heterozygosity lost over time
(genetic heterozygosity in a population)
Why is demographic stochasticity an important cause of every individual contributes a lot to the population's chance of survival when
extinction for small populations ONLY? populations are small
What five assumptions are required for creating an ideal 1) Discrete generations
population? 2) Completely random mating
3) Nm = Nf (even sex ratio)
4) Random family sizes
5) Constant population size
If a population is not ideal, convert N to Ne and then calculate the rate of loss of
H. It is almost always the case that Ne < N
Which of the following risks is the result of random demographic stochasticity: random variation among individuals in birth rate, death
variation in the survival and production of offspring and is rate, and sex of offspring. (declines quickly with population size)
especially of concern for a small population?
Why do conservation scientists care about genetic 1) Long-term: evolutionary potential
diversity within species? -populations may diverge into new subspecies or even full species
2) Long-term: evolutionary flexibility
-ability to respond to epidemics, climate change
3) Short-term: individual and population health
-genetic diversity improves an individual's fitness
Two measures of genetic diversity 1) Polymorphism: number of loci for which >1 allele exists
2) Heterozygosity: average percentage of loci that are heterozygous or
heterozygous at a particular locus
What three factors affect heterozygosity? Sex ratio, mating structure, population variability through time
Why do small populations lose genetic diversity over Little new genetic diversity emerges because mutations are rare and gene flow is
time? limited/non-existent
